Automatic control for flash-boilers.



, L G. H. HILL. 5 AUTOMATIC CONTROL FOR FLASH BOILERS. APPLICATION mmMAY 25, 1915.

;' 1 ,1 90, 1 6'? I l atentm July 4, 1916.

2 SHEETS-SHEET 1.

Fig. l.-

\ Inventor: (Beer 6 H. Hill,

e. H. HILL.

AUTOMATIC CONTROL FOR FLASH BOILERS.

APPLICATION FILED MAY 25, 1915.

1;190,167. Pdtentedluly l, 1916.

ZSHEETS-SHEET 2.

lnVntor: George H. NM,

His Attorney UNITED STATES PATENT 1 OFFICE.

QEORGE H. HILL, SCHEHECTADY, NEW YORK, ASSIGNOB TO GENEBALELECTBIGCOMPANY, A CORPORATION OFN'EW YORK.

nu'ronn'rrc con'rnon FOR rmsn-no nnns.

Specification of Letters Patent.

Patented July 4, 1916.

To all whom it may concern:

Be it known that I, Gnoncn H. HJLL, a

' citizen of the United States, residing at Schenectady, county ofSchenectady, State of New York, have invented certain new and usefulImprovements in Automatic Control for Flash-Boilers, of which thefollowing is a specification. v

My invention relates to electric water heaters and hasfor its object theprovision of means whereby the temperature and flow of water in suchdevices may be controlled in a reliable and eflicient manner.

My invention relates more specifically to water heaters for generatingsteam, and more particularly to water heaters of the type known as flashboilers in which steam is generated rapidly. In a flash boiler, wa-

ter is forced through passages such as pipe sections which are heated toa relatively high temperature so that steam will be generated almostinstantly when the water touches the heated surfaces. When electricenergy is used for heating the water by passing the electric currentthrough the pipe, it is necessary that the pipe be of a considerablelength in order to obtain sufficient electrical resistance. A highpressure is therefore required to force the water through the pipe, andto overcome this difiiculty, it has heretofore been proposed to dividethe pipe into sections connected in parallel with reference to the Watersupply so that the water may be pumped through each sectionindependently of the others, each section having its own inlet anddischarge connections. Such a heating system is disclosed in a patent toBatchelder No. 1,019,413 which was issued March 5, 1912.

One of the difiiculties encountered in such a system is that thedelivery of water to the various sections is not always uniform. This isdue to mechanical difierences in the various pumps, to the presence ofair in the water, or to various other causes. The result becomescumulative and asection is liable to be burned out.

In a ccordance with my invention, provi- S1011 is made for counteractingthe tendency of any of the sections toward becoming overtrolling theby-pass in 1; Fig. 3 is a diagrammatic view similar to Fig. 1, showing amodification of, my invention; Fig. 4: is a sectional view of the valvecontrolling the by-pass of Fig. 3 Fig. 5 illustrates still anothermodification, and Fig. 6 is a sectional view showing a valve applicableto the system there illustrated. I

Referring, now, to the drawings, and first to Fig. 1, A is a flashboiler composed of a plurality of pipe sections 10, 11, 12, and 13,which are insulated from each other at 14:, and are provided with inlets15, insulated from the pumps at 16. Separate outlet pipes 17 are alsoprovided, which communicate with a delivery pipe 18 by means of a pipe19 which is insulated from the outlet pipes 17 as indicated. A tank 20constitutes the source of water supply from which water is fed to thevarious pipe sections by means of pumps 21, 22, 23, and 21. The pumpsare operated through suitable gearing 27 by a motor 25 connected to theline 26.

The system thus far described is the same as that disclosed in theBatchelder patent above referred to, and no novelty is claimed therefor.

In order to overcome the difiiculties which have heretofore beenexperienced as above outhned, I provide relays 28, 29, 30 and 31, onefor each heater section. These relays are made responsive to thetemperature of the various sections of the heater by providing eachrelay with a coil connected across a heater section so that the'rise intemperature of the section will, by increasing the voltage drop acrossthe section, cause the relay to operate. In order that the relays shallnot be affected by variations in voltage, I also provide each of themwith a coil connected to the main source of potential and which isdifferentially wound with respect to the other. As illustrated,therefore, relays 28, 29, 30 and 31 each comprises two windings, thelower winding being a potential winding connected across the line whileeach upper .winding is connected across a heater section. The potentialwind-- ings are all in series and the arrangement of each relay is suchthat under normal conditions, the relays will .be inoperative due to thedifferential action of the two windings. Each of these relays controls avalve which in turn controls the supply of water to a heater section. Inthe particular arrangement shown, in Figs. 1 and 2 the relays controlcoils 36 which, when energized, open a normally closed valve 37 in aby-pass around the pump which feeds the section controlled by thisparticular relay.

The operation of this form of my inven tion is as follows: Normally themotor will be operating continuously, driving the pumps 21, 22, 23 and24. The by-passes around these the heater sections are being fed alike.The relays 28, 29, and 31 are deenergized so that their switch arms arein engagement.

with the lower contacts which are connected with the various valve coils36. If now, one of the pipe sections should become overheated, due toany cause, the voltage drop across that part of the section is increasedcausing the relay'eontrolled by this section to operate. Assuming forexample, that the section 10 becomes overheated: the relay 28 will beoperatively energized since the ampere turns of the upper winding willbe increased, while the lower winding will be unaffected. The operationof relay 28, causes the switch arm 32 to engage its upper contactthereby completing the circuit from the line through switch arm 32 andthence in parallel through the switch arms 33, 34 and 35 which are in alower position, to the three coils 36 controllin of the umps 22, 23 and24, de iverin water to t e sections 11, 12, and 13 respectlvely; Theby-passes around the umps 22, 23 and 24 are now opened, there y causingthese pumps to decrease the amount of water de-' livered by them to thesections 11, 12, and 13.

and thereby raising the temperature of these sections. This causes theresistance and hence the voltage of these sections to be increased andthis in turn decreases the voltage drop across the section 10. Thetemperature-of all of the sections is thereby equalized. It will benoted that with the differential arrangement of the relays any variationin line voltage will affect the two coils of the relays equally so thatthe. relays pumps are closed and all of the valves f will not beaffected by any variation of line voltage, but will only be affected bythe va-. riations in the potential drop across the various heatersections which in turn will be governed by the temperature.

In Fig. 3, I have shown a modified form of the invention in which thedesired result is produced by increasing the flow of water to theoverheated section instead of decreasing the flow of water to the othersections. The arrangement of heater sections and relays is the same asthat of Fig. 1, butinthis case, the by-pass around each pump is normallyopen so that under ordinary con ditions, a certain amount of water isbeing by-passed around each pump. When, therefore, a section becomesoverheated, the relayassociated with this particular section operates inthe manner described in connection with Fig. 1. In this case, however,only one winding 36 is energized to close a valve 37*. For instance ifthe section 10 should become overheated, the relay 28- would operate toenergize the coil 36 controlling the valve 37 in the by-pass around thepump 21. This will cause the rate of delivery of water to section 10 tobe increased. I

In Fig. 5, I have illustrated another modification in which the water isdelivered to the heater sections from a tank 20 in whichthe pressure ismaintained constant. The tank is supplied from a pump 39 and an air dome40 is provided for maintaining a predetermined pressure higher thanneeded to normally supply the boiler. In this case the valves 37 B arelocated in the pipes leading from the tank to the various heatersections. The valves are normally closed b' springs 41 and open at-apredetermined di ference in pressure between the tank and b01ler sectionto permit water to pass from the tank to the various sections The coils36, one of which is energized by the operation of each of the relays,act upon the valves in opposition to thespring 41. In the event ofoverheating of a section, the valvecontrolling the flow to that sectionW111. be opened by reason of the coil acting against the spring 41, thusallowing the full pressure of the tank into the section and therebyincreasing the rate of delivery of water to the overheated section.

In accordance with the provisions of the patent statutes, I havedescribed the principle-of operation of my invention, together with theapparatus which I now considerto represent the best embodiment thereof;but I desire to have it understood that the apparatus shown is onlillustrative, and that the invention can be carried out. by other means.J 3

What I claim as new, and desire to secure by Letters Patent of theUnited States, 1s: 1

1. An electric heaitingsysten comprising a plurality of pipe sections inwhich the water is electrically heated, a source of water supply feedingsaid sections in parallel,

and means for equalizing the temperatures of all of the sections.

2. An electric heating system comprising a plurality of pipe sections inwhich water is electrically heated, a source of water supply for feedingsaid sections in parallel, and electrically controlled means for varyingthe relative flow of water to these sections to equalize the temperatureof said sections.

3. An electric heating system comprising a plurality of pipe sections inwhich the water is electrically heated, a source of water supply feedingsaid sections in parallel, and means controlled by the temperature of asection for controlling the relative flow of water to the varioussections.

4. An electric heating system comprising a plurality of pipe sections, asource of water supply feeding said sections in parallel, means forpassing an electric current through said sections in series, and meanscontrolled by the temperature of any one section for controlling therelative flow of Water to the various sections.

5. An electric heating system comprising a plurality of pipe sectlons,electric heating means associated therewith, a source of water supplyfeeding said sections in parallel, and electromagnetic means controlledby the temperature of a section for controlling the flow of water to thevarious sections.

6. An electric heating system comprising a plurality of pipe sections inwhich the water is electrically heated, a source of water supply feedingsaid sections in parallel, and means comprising electromagnetic relaysprovided with coils connected across the respective pipe sections forequalizing the temperatures of all of the sections.

7. An electric heating system comprising a plurality of pipe sections inwhich water is electrically heated, a source of water supply for feedingsaid sections in parallel,

electromagnetic relays controlled by the temperature of these sections,and valves controlled by said relays for controlling the water flow tothe various sections.

8. An electric heating system comprising a plurality of pipe sections inwhich the water is electrically heated, each having a separate inlet, aseparate pumping device connected with each inlet, by-passes around thevarious pumps, and means controlled by the temperatures of the varioussections for actuating said by-passes to vary the amount of liquiddelivered to the various sections.

9. An electric heating system comprising a plurality of pipe sections inwhich water is heated by the passage of current therethrough, a sourceof water supply feeding said sections in parallel, and electromagneticmeans jointly under the control of the supply voltage and the voltageacross the various sections for equalizing the temperatures in all ofthe sections.

10. An electric heating system comprising a plurality of pipe sectionsin which water is heated by the passage of current therethrough, asource of water supply feeding said sections in parallel, and meanscomprising differential relays whose coils are jointly controlled by thesupply voltage and the voltage across the various pipe sections,respectively, for equalizing the temperatures in all of the sections.

11. An electric heating system comprising a plurality of pipe sections,a source of water supply feeding said sections in parallel, means forpassing an electric current through said sections in series, and meansjointly under the control of the line voltage and the voltages acrossthe various sections for controlling the relative delivery of Water tothe various sections, and thereby controlling their temperatures.

, 12. An electric heating system comprising a plurality of pipe sectionsin which Water is heated by the passage of current through the sectionsin series, a source of water supply feeding said sections in parallel,electromagnetic relays energized diiferentially by the supply voltageand the voltage across the pipe sections and valves controlled by saidrelays for controlling the How of Water from the sourceto the varioussections.

In witness whereof, I have hereunto set my hand this 24th day of May,1915.

GEORGE H. HILL.

